Method of and apparatus for bending tubes.



H. P. & A. S. MACDONALD.

METHOD OF AND APPARATUS FOR BENDTNG TUBES.

APPLICATION FILED 050.13, 1917.

1,295,048. Patented Feb. 18,1919,

scaling.

umrnn STATES PATENT OFFICE.

HARRY P. MACDONALD, OF MONTCLAIR, NEW JERSEY, AND ANGUS S.

MACDONALD, on

GREAT NECK STATION, NEW YORK, ASSIGNORS TO THE SNEAD & CO. IRON WORKS, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF AND APPARATUS FOR BENDING TUBES.

Specification of Letters Patent.

' Patented Feb..18, 1919.

Original application filed December 23, 1916, Serial No. 138,596. Divided and this application filed December Y 13, 1917. Serial No. 206,887.

and Apparatus for Bending Tubes, of which the following is a specification.

This invention relates to a method of and,

apparatus for bending tubes, rods and the like, and is a division of our co-pending application, Serial Number 138,596, filed December 23rd, 1916. It has for one of its primary objects the provision of an improved method and apparatus whereby the tubes can be economically and expeditiously bent, with a minimum loss of metal from Our invention also contemplates the provision of an improved method whereby the article to be bent may be heat-treated for bending while in the bending apparatus.

We accomplish the foregoing, together with such other objects as may hereinafter appear, by means of an improved method and apparatus, the preferred embodiments of which are illustrated in the accompanying drawings, wherein,-

Figure 1 is a side elevation of and partial section through one form of bending apparatus adapted forcarrying out our improved mcthod; Fig. 2 is a longitudinal section through another type of bending apparatus suitable for our improved method: Fig. 3 is an end elevation and partial section of the apparatus shown in Fig. 2; and Fig. 4 is a partial side elevation and section of another form of bending apparatus to which our invention may be applied.

Generally speaking our invention consists pivotally mounted on the shaft 11. which in wires 12 and 12 to a suitable source of current, the quantity of-which is regulated by some suitable device such for example, as

the rheostat diagranunatically indicated at 13. It is, of course, to be understood that where the article to be bent is hollow it is first filled with sand or the like, but. an inert material which will assist in preventing oxidation is preferred.

The operation is as follows: The tube is first positioned in the block A, the block B is then adjusted to the proper point and fixedby means of thestud 14, after which the current is turned on and passes through that portion of the tube between the contacts, such portion being heated by its internal resistance to the current. When the tube has been heated to the properpoint the arm around the die or form 8.

As a means for indicating when the tube has been heated to the proper degree we provide a device described and generically claimed in the aforesaid co-pending ap lication. For the purpose of this specitibation it will suffice to say that this device comprises a block C, slidably mounted on the rod 15 to assume any desired vertical position. Pivoted to the block is'a segment 16 having3a nose 17 adapted to engage the terminal A pinion 18 is in mesh with the segment and is adapted to operate an indi cator arm 19. The block C is also equipped with a dial (not shown). As the tube expands as it becomes heated, the terminal B of course moves upward with the tube and operates the indicator arm 19 through the segment and pinion, and at the desired point the current may be'cut oil. The indicating mechanism will accurately register the temperature of tube, particularly if the tube is to be bent at the critical point, commonly called, the point of recalescence. When this point has been reached the metal will absorb a great many heat units without corresponding rise in the temperature, and

therefore without a change in the dimensions, and expansion of the tube temporarily pauses. When, therefore, the indicator arm 19 is temporarily stationary, the operator at once knows that the tube has been heated to the proper bending temperature and cuts off the current, and then bends the tube in the manner previously indicated. v

In Figs. 2, 3 and 4 we have indicated two forms of apparatus especially adapted for the bending of tubular front axles of automobiles. In the construction shown in Fig. 3, we employ a die or form 20 of the proper shaft above which is mounted a pair of rolls 21, such rolls being moved oppositely as indicated by the arrows to bend the tube over the form 20. In this arrangement'both the terminals A and B are carried by the tube and are movable therewith. In Fig. 4 a pair of rolls or forms 22 are substituted for the form 20, a pair ofrelatively stationary rolls 23 are provided, with a movable roll 24 mounted above the arm 22 and intermediate the vertical axis. The roll 24 is moved downwardly and cooperates with the rolls or forms 22 and 23 to bend'the tube .to the shape indicated.

It will beapparent that by our improved method and apparatus We eliminate the complicated and expensive heating furnaces and handling mechanism usually employed in carrying out bending operations, and

avoid the loss of time entailed by the use of such apparatus. Furthermore, scale is-prevented which cuts down the loss of ma terial, and in addition we are enabled to carry out the bending point when the meta has been raised to the operation at the veryproper degree of temperature. This results in superiority and uniformity in product.

We claim p 1. The herein described process of tube bending which consists in-heating the tube to be bent by its internal resistance to a current of electricity passed therethrough while in the bending apparatus, with freedom for belroiding movement, and then in bending the m e.

2. In tube bending apparatus, the combination of means for bending the tube, means for supporting the tube, a pair of contacts adapted to engage the tube at spaced intervals whereby the portion of the tube therebetween is heated by its internal resistance to a current" of electricity flowing therethrough from terminal to terminal, said terminals being supported in such manner as not to interfere with the bending operation.

3. In tube bending apparatus, the combination of means for bending the tube, a combined terminal and support for said tube, a second terminal carried by the tube, and means for connecting said terminals with a suitable source of electric current, the. bending means being located intermediate the terminals. I

4. In tube'bending apparatus, the combination of terminals engaging the tube,

means for connecting said terminals with a source of electric current, bending means for bending the tube located intermediate signed our names.

HARRY P. MACDONALD. ANGUS S. MACDONALD. 

